Key Points for This Section

Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin. Skin color and exposure to sunlight can affect the risk of developing nonmelanoma skin cancer and actinic keratosis. Nonmelanoma skin cancer and actinic keratosis often appear as a change in the skin. Tests or procedures that examine the skin are used to detect (find) and diagnose nonmelanoma skin cancer and actinic keratosis. Certain factors affect prognosis (chance of recovery) and treatment options.

Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin.

The skin is the body’s largest organ. It protects against heat, sunlight, injury, and infection. Skin also helps control body temperature and stores water, fat, and vitamin D. The skin has several layers, but the two main layers are the epidermis (upper or outer layer) and the dermis (lower or inner layer). Skin cancer begins in the epidermis, which is made up of 3 kinds of cells:

• Squamous cells: Thin, flat cells that form the top layer of the epidermis.
• Basal cells: Round cells under the squamous cells.
• Melanocytes: Found in the lower part of the epidermis, these cells make melanin, the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes make more pigment, causing the skin to darken.

Enlarge

Anatomy of the skin, showing the epidermis, dermis, and subcutaneous tissue.

Skin cancer can occur anywhere on the body, but it is most common in skin that has been exposed to sunlight, such as the face, neck, hands, and arms. There are several types of cancer that start in the skin. The most common types are basal cell carcinoma and squamous cell carcinoma, which are nonmelanoma skin cancers. Actinic keratosis is a skin condition that sometimes develops into squamous cell carcinoma.

This summary refers to the treatment of nonmelanoma skin cancer and actinic keratosis. Nonmelanoma skin cancers rarely spread to other parts of the body. Melanoma, the rarest form of skin cancer, is more likely to invade nearby tissues and spread to other parts of the body. See the following PDQ summaries for information on melanoma and other kinds of skin cancer:

• Melanoma Treatment ¹
• Mycosis Fungoides and the Sézary Syndrome Treatment ²
• Kaposi Sarcoma Treatment ³

Skin color and exposure to sunlight can affect the risk of developing nonmelanoma skin cancer and actinic keratosis.

Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Risk factors for basal cell carcinoma and squamous cell carcinoma include the following:

• Being exposed to a lot of natural or artificial sunlight.
• Having a fair complexion (blond or red hair, fair skin, green or blue eyes, history of freckling).
• Having scars or burns on the skin.
• Being exposed to arsenic.
• Having chronic skin inflammation or skin ulcers.
• Being treated with radiation.
• Taking immunosuppressive drugs (for example, after an organ transplant).
• Having actinic keratosis.

Risk factors for actinic keratosis include the following:

• Being exposed to a lot of sunlight.
• Having a fair complexion (blond or red hair, fair skin, green or blue eyes, history of freckling).

Nonmelanoma skin cancer and actinic keratosis often appear as a change in the skin.

Not all changes in the skin are a sign of nonmelanoma skin cancer or actinic keratosis, but a doctor should be consulted if changes in the skin are seen.

Possible signs of nonmelanoma skin cancer include the following:

• A sore that does not heal.
• Areas of the skin that are:
  • Small, raised, smooth, shiny, and waxy.
  • Small, raised, and red or reddish-brown.
  • Flat, rough, red or brown, and scaly.
  • Scaly, bleeding, or crusty.
  • Similar to a scar and firm.

Possible signs of actinic keratosis include the following:

• A rough, red, pink, or brown, raised, scaly patch on the skin.
• Cracking or peeling of the lower lip that is not helped by lip balm or petroleum jelly.

Tests or procedures that examine the skin are used to detect (find) and diagnose nonmelanoma skin cancer and actinic keratosis.

The following procedures may be used:

• Skin examination: A doctor or nurse checks the skin for bumps or spots that look abnormal in color, size, shape, or texture.
• Biopsy: All or part of the abnormal-looking growth is cut from the skin and viewed under a microscope by a pathologist to see if cancer cells are present. There are 3 main types of skin biopsies:
  • Shave biopsy: A sterile razor blade is used to “shave-off” the abnormal-looking growth.
  • Punch biopsy: A special instrument called a punch or a trephine is used to remove a circle of tissue from the abnormal-looking growth.

    Enlarge

    Punch biopsy. A hollow, circular scalpel is used to cut into a lesion on the skin. The instrument is turned clockwise and counterclockwise to cut down about 4 millimeters (mm) to the layer of fatty tissue below the dermis. A small sample of tissue is removed to be checked under a microscope. Skin thickness is different on different parts of the body.

  • Excisional biopsy: A scalpel is used to remove the entire growth.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) depends mostly on the stage of the cancer and the type of treatment used to remove the cancer.

Treatment options depend on the following:

• The stage of the cancer (whether it has spread deeper into the skin or to other places in the body).
• The type of cancer.
• The size and location of the tumor.
• The patient’s general health.

Glossary Terms

Not normal. An abnormal lesion or growth may be cancerous, premalignant (likely to become cancer), or benign.

A precancerous condition of thick, scaly patches of skin. Also called senile keratosis and solar keratosis.

A poisonous chemical used to kill weeds and pests. Also used in cancer therapy.

A small, round cell found in the lower part (or base) of the epidermis, the outer layer of the skin.

A type of skin cancer that arises from the basal cells, small round cells found in the lower part (or base) of the epidermis, the outer layer of the skin.

The removal of cells or tissues for examination by a pathologist. The pathologist may study the tissue under a microscope or perform other tests on the cells or tissue. There are many different types of biopsy procedures. The most common types include: (1) incisional biopsy, in which only a sample of tissue is removed; (2) excisional biopsy, in which an entire lump or suspicious area is removed; and (3) needle biopsy, in which a sample of tissue or fluid is removed with a needle. When a wide needle is used, the procedure is called a core biopsy. When a thin needle is used, the procedure is called a fine-needle aspiration biopsy.

A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

A disease or condition that persists or progresses over a long period of time.

The lower or inner layer of the two main layers of tissue that make up the skin.

Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic.

The upper or outer layer of the two main layers of tissue that make up the skin.

A surgical procedure in which an entire lump or suspicious area is removed for diagnosis. The tissue is then examined under a microscope.

Describes the ability to decrease the body's immune system responses.

Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body’s natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.

Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.

A pigment that gives color to skin and eyes and helps protect it from damage by ultraviolet light.

A cell in the skin and eyes that produces and contains the pigment called melanin.

A form of cancer that begins in melanocytes (cells that make the pigment melanin). It may begin in a mole (skin melanoma), but can also begin in other pigmented tissues, such as in the eye or in the intestines.

Skin cancer that forms in basal cells or squamous cells but not in melanocytes (pigment-producing cells of the skin).

A part of the body that performs a specific function. For example, the heart is an organ.

A doctor who identifies diseases by studying cells and tissues under a microscope.

PDQ is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, complementary and alternative medicine, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services, and organizations that provide cancer care. Most of this information, and more specific information about PDQ, can be found on the NCI's Web site at http://www.cancer.gov/cancertopics/pdq. Also called Physician Data Query.

A substance that gives color to tissue. Pigments are responsible for the color of skin, eyes, and hair.

The likely outcome or course of a disease; the chance of recovery or recurrence.

Removal of a small disk-shaped sample of tissue using a sharp, hollow device. The tissue is then examined under a microscope.

The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called irradiation and radiotherapy.

Something that may increase the chance of developing a disease. Some examples of risk factors for cancer include age, a family history of certain cancers, use of tobacco products, certain eating habits, obesity, lack of exercise, exposure to radiation or other cancer-causing agents, and certain genetic changes.

A small, thin knife used for surgery.

A procedure in which a skin abnormality and a thin layer of surrounding skin are removed with a small blade for examination under a microscope. Stitches are not needed with this procedure.

Cancer that forms in tissues of the skin. There are several types of skin cancer. Skin cancer that forms in melanocytes (skin cells that make pigment) is called melanoma. Skin cancer that forms in basal cells (small, round cells in the base of the outer layer of skin) is called basal cell carcinoma. Skin cancer that forms in squamous cells (flat cells that form the surface of the skin) is called squamous cell carcinoma. Skin cancer that forms in neuroendocrine cells (cells that release hormones in response to signals from the nervous system) is called neuroendocrine carcinoma of the skin. Most skin cancers form in older people on parts of the body exposed to the sun or in people who have weakened immune systems.

Flat cell that looks like a fish scale under a microscope. These cells cover inside and outside surfaces of the body. They are found in the tissues that form the surface of the skin, the lining of the hollow organs of the body (such as the bladder, kidney, and uterus), and the passages of the respiratory and digestive tracts.

Cancer that begins in squamous cells, which are thin, flat cells that look like fish scales. Squamous cells are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts. Also called epidermoid carcinoma.

The extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has spread from the original site to other parts of the body.

A group or layer of cells that work together to perform a specific function.

A surgical procedure in which tissue or an organ is transferred from one area of a person’s body to another area, or from one person (the donor) to another person (the recipient).

A surgical tool used to cut out circular pieces of bone or other tissue.

The formation of a break on the skin or on the surface of an organ. An ulcer forms when the surface cells die and are cast off. Ulcers may be associated with cancer and other diseases.

A nutrient that the body needs in small amounts to function and stay healthy. Vitamin D helps the body use calcium and phosphorus to make strong bones and teeth. It is fat-soluble (can dissolve in fats and oils) and is found in fatty fish, egg yolks, and dairy products. Skin exposed to sunshine can also make vitamin D. Not enough vitamin D can cause a bone disease called rickets. It is being studied in the prevention and treatment of some types of cancer. Also called cholecalciferol.